This invention relates to a torque converter for transmitting the power of an engine to a transmission or gearbox by means of oil, and more particularly, to an arrangement of oil passageways through which oil is supplied into a torque converter, or removed from it.
A known torque converter is shown in FIG. 3 of the accompanying drawings. It has a pump impeller 201, a turbine runner 202 and a stator 203. The pump impeller 201 is connected with a converter cover 204 to the output shaft of an engine not shown, and the turbine runner 202 is connected to the input shaft 206 of a transmission or gearbox by a turbine runner hub 205. The stator 203 is connected to a stator shaft 210 by a one-way clutch 207. The stator shaft 210 has a shaft member 211 situated about the input shaft 206 and a flange member 212 having a boss portion 212a press fitted about the shaft member 211 and a flange portion 212b attached to a transmission casing C. A pump impeller boss member 201a, which is attached to the pump impeller 201, is situated about the boss portion 212a, and is rotatably supported/by a bearing 208 located between the pump impeller boss member 201a and the shaft member 211.
Oil is supplied into the torque converter through a path formed by an oil passageway 221 in the flange portion 212b, to an oil passageway 222 between the shaft member 211 of the stator shaft 210 and the boss portion 212a of the flange member 212, to an opening 222a in the boss portion 212a, to a clearance around the bearing 208, to a space 223 between the pump impeller boss member 201a and the shaft member 211. The oil is discharged from the torque converter through a path formed by a space 224 between the turbine runner hub 205 and the one-way clutch 207, to an oil passageway 225 between the input shaft 206 and the shaft member 211, an oil passageway 226 in the shaft member 211 and an oil passageway 227 between the shaft member 211 and the boss portion 212a of the flange member 212.
In a conventional oil passage of this type the bearing 208, however, causes an increased resistance to the flow of oil. Moreover, the bearing 208 prevents the boss portion 212a of the flange member 212 from having its left end extended near the stator 203, and as the oil passageway 227 formed between the shaft member 211 and the boss portion 212a extends only to a position slightly short of the bearing 208, the oil passageway 225 between the input shaft 206 and the shaft member 211 must be extended to near the left end of the oil passageway 227. The oil passageway 225 is formed by a portion of the input shaft 206 having a smaller radius than the remaining portion, and thereby lowers the input shaft""s strength and rigidity.
Moreover, the oil passageway 223 between the shaft member 211 and the pump impeller boss member 201a has a reduced diameter in its portion where it is supported by the bearing 208, the bearing 208 not having a smaller thickness to be less expensive. Its portion having a reduced diameter gives an increased resistance to the flow of oil, but there is no alternative but to use it as an oil passageway, since the boss portion 212a of the flange member 212 is not allowed to have its left end extended beyond the vicinity of the bearing 208, as stated before. The boss portion 212a is so small in length that there is hardly any freedom of forming the opening 222a in any other position along the boss portion 212a. While it may be possible to have the boss portion 212a extend in the opposite direction away from the torque converter, the transmission becomes undesirably large in overall length.
Under these circumstances, it is an object of this invention to provide a structure defining an improved arrangement of oil passageways in a torque converter and enabling a transmission to have an input shaft of improved strength and rigidity.
This invention is an attempt to solve the above problems. Besides improving the flow of oil to and from the torque converter, it is our purpose to provide a torque converter oil passageway with a structure that improves the strength and rigidity of the input shaft.
This object is attained by a structure comprising a torque converter having a pump impeller, a turbine runner and a stator, a transmission having an input shaft connected to the turbine runner and supported rotatably by a transmission casing, having about the transmission input shaft connected to the stator an inner cylindrical portion connected to the stator and situated about the input shaft (such as a shaft member 41) and an outer cylindrical portion press fitted about the inner cylindrical portion and connected to the transmission casing (such as boss portion 42a of flange member 42), and having a plurality of oil passageways (such as an oil passageway 102) formed between the outer periphery of its inner cylindrical portion and the inner periphery of its outer cylindrical portion and along the input shaft for supplying oil into the torque converter and removing it therefrom, and a pump impeller boss member connected to the pump impeller, situated about the outer cylindrical portion of the stator shaft and having an outer periphery supported rotatably by a bearing in the casing, the outer cylindrical portion of the stator shaft having an end situated closer to the stator than that portion of the pump impeller boss member which is supported by the bearing, and the oil passageways having at least one outlet opening (such as an opening 40b or 40c) situated closer to the stator than that portion of the pump impeller boss member which is supported by the bearing.
No bearing is required between the pump impeller boss member and the inner cylindrical portion of the stator shaft, since the former has its outer periphery supported by a bearing. As a result, the outer cylindrical portion of the stator shaft may have an end extended close to the stator and the oil passageways formed between the inner and outer cylindrical portions of the stator shaft may have at least one outlet opening situated close to the stator.
The torque converter has an improved arrangement of oil passageways enabling an efficient supply or removal of oil, since there is no bearing giving an increased resistance to the flow of oil. An oil passageway 111 formed between and along the transmission input shaft and the inner cylindrical portion of the stator shaft is smaller in length. As that passageway is formed by a portion of the input shaft having a reduced radius, its reduction in length improves the strength and rigidity of the input shaft. As the outer cylindrical portion of the stator shaft has its end situated close to the stator, there is a greater degree of freedom in determining the arrangement of oil passageways.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.